/**
 * Copyright (c) 2005-2011 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id: PropertiesLoader.java 1690 2012-02-22 13:42:00Z calvinxiu $
 */
package com.fand.utils;

import java.io.IOException;
import java.io.InputStream;
import java.util.NoSuchElementException;
import java.util.Properties;

import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;

/**
 * Properties文件载入工具类. 可载入多个properties文件,
 * 相同的属性在最后载入的文件中的值将会覆盖之前的值，但以System的Property优先.
 * 
 * @author yaoHT
 */
public class PropertiesLoader {
	
	private static Logger logger = LoggerFactory.getLogger(PropertiesLoader.class);
	
	private static ResourceLoader resourceLoader = new DefaultResourceLoader();
	
	private final Properties properties;
	
	public PropertiesLoader(final String... resourcesPaths) {
		this.properties = this.loadProperties(resourcesPaths);
	}
	
	/**
	 * 取出Boolean类型的Property.如果都為Null抛出异常,如果内容不是true/false则返回false.
	 */
	public Boolean getBoolean(final String key) {
		final String value = this.getValue(key);
		if (value == null) { throw new NoSuchElementException(); }
		return Boolean.valueOf(value);
	}
	
	/**
	 * 取出Boolean类型的Propert.如果都為Null則返回Default值,如果内容不为true/false则返回false.
	 */
	public Boolean getBoolean(final String key, final boolean defaultValue) {
		final String value = this.getValue(key);
		return value != null ? Boolean.valueOf(value) : defaultValue;
	}
	
	/**
	 * 取出Double类型的Property.如果都為Null或内容错误则抛出异常.
	 */
	public Double getDouble(final String key) {
		final String value = this.getValue(key);
		if (value == null) { throw new NoSuchElementException(); }
		return Double.valueOf(value);
	}
	
	/**
	 * 取出Double类型的Property.如果都為Null則返回Default值，如果内容错误则抛出异常
	 */
	public Double getDouble(final String key, final Integer defaultValue) {
		final String value = this.getValue(key);
		return value != null ? Double.valueOf(value) : defaultValue;
	}
	
	/**
	 * 取出Integer类型的Property.如果都為Null或内容错误则抛出异常.
	 */
	public Integer getInteger(final String key) {
		final String value = this.getValue(key);
		if (value == null) { throw new NoSuchElementException(); }
		return Integer.valueOf(value);
	}
	
	/**
	 * 取出Integer类型的Property.如果都為Null則返回Default值，如果内容错误则抛出异常
	 */
	public Integer getInteger(final String key, final Integer defaultValue) {
		final String value = this.getValue(key);
		return value != null ? Integer.valueOf(value) : defaultValue;
	}
	
	public Properties getProperties() {
		return this.properties;
	}
	
	/**
	 * 取出String类型的Property,如果都為Null则抛出异常.
	 */
	public String getProperty(final String key) {
		final String value = this.getValue(key);
		if (value == null) { throw new NoSuchElementException(); }
		return value;
	}
	
	/**
	 * 取出String类型的Property.如果都為Null則返回Default值.
	 */
	public String getProperty(final String key, final String defaultValue) {
		final String value = this.getValue(key);
		return value != null ? value : defaultValue;
	}
	
	/**
	 * 取出Property。
	 */
	private String getValue(final String key) {
		final String systemProperty = System.getProperty(key);
		if (systemProperty != null) { return systemProperty; }
		return this.properties.getProperty(key);
	}
	
	/**
	 * 载入多个文件, 文件路径使用Spring Resource格式.
	 */
	private Properties loadProperties(final String... resourcesPaths) {
		final Properties props = new Properties();
		
		for (final String location : resourcesPaths) {
			
			PropertiesLoader.logger.debug("Loading properties file from path:{}", location);
			
			InputStream is = null;
			try {
				final Resource resource = PropertiesLoader.resourceLoader.getResource(location);
				is = resource.getInputStream();
				props.load(is);
			} catch (final IOException ex) {
				PropertiesLoader.logger.info("Could not load properties from path:{}, {} ", location,
				        ex.getMessage());
			} finally {
				IOUtils.closeQuietly(is);
			}
		}
		return props;
	}
}
